Water-soluble vegetable protein aggregates

ABSTRACT

Aqueous protein dispersions obtained from vegetable sources are subjected to successive pressure and cavitation cycling (e.g., centrifugal homogenization) at temperatures below the protein heat denaturization and under slightly alkaline pH&#39;s (e.g., pH 7.0-8.0) to provide a high NSI product. These high NSI products may be dried to provide a vegetable seed product having functional properties and utility similar to milk proteins. Buffered salt extracts from such spray-dried products reveal a predominant restructuring of the protein constituents into high molecular weight protein aggregates. Low NSI soy concentrates obtained by aqueous alcohol extraction processes are converted into a high NSI product possessing many of the desirable functional attributes of soy isolates plus those of milk proteins.

BACKGROUND OF THE INVENTION

Proteinaceous products obtained from seed materials have beenextensively used as partial replacement or extender for proteins derivedfrom animal, marine and poultry sources. Defatted proteinaceousmaterials are conventionally manufactured by extracting lipids and oilsfrom full-fat seed meals or flakes. Protein concentrates aremanufactured by extracting the water-soluble or aqueous-alcohol solubleconstituents from defatted seed materials. Protein isolates are obtainedby isolating the vegetable protein from the non-protein constituents.

Defatted vegetable proteinaceous materials are commonly referred to bythe art as vegetable protein products (e.g. Section 102.75, ProposedRules, Federal Register, July 14, 1978, Part III) with the word"vegetable" being often replaced to identify the seed protein source(e.g. soy protein products). Vegetable protein products containing lessthan 65% protein are referred to as flour, those containing 65% or moreprotein by weight to less than 90% seed protein by weight are classifiedas protein concentrates, and isolates as containing 90% by weightprotein or higher.

Indigenous seed constituents adversely affect flavor, odor, flatulentand digestive characteristics of the vegetable protein products. Proteindenaturization manufacturing conditions (e.g. heat, alcohol extraction)are customarily used to eliminate these indigenous constituents. Proteindenaturization substantially reduces solubility of the vegetableprotein.

Vegetable protein products are susceptible to substantial chemical andphysical alteration by what may appear to be only minor processingchanges. An infinite number of different vegetable protein products maybe prepared by simply altering the preparatory processing conditions.The vegetable protein readily reacts or complexes with itself or otherconstituents indigenous to the seed material as well as processingadditives or process conditions which are conventionally used during thevegetable protein product manufacture. The implementation of certainprocessing changes to correct a specific functional defect oftenadversely affects one or more equally important functional attributes ofthe vegetable protein product.

The colloidal or water-soluble vegetable protein concentration (i.e. byweight water-soluble protein) is an important factor in many foodrecipes (e.g. comminuted meats, diary products, bakery, etc.).Analytically, the water-soluble protein concentration can be ascertainedby the nitrogen solubility index (NSI) or protein-in-solution (PIS)tests as shown in Example I. Although the prior art abounds withdivergent processing conditions which may be used to correct flavor,odor, digestibility, etc. deficiencies, little progress has been madetowards improving the NSI of vegetable protein products. The proposedNSI improvements have been either expensive or impractical in themanufacture of a low-cost vegetable protein product. The problem ofachieving a high NSI value becomes particularly acute when anunhydrolyzed, unfractionated protein concentrate or isolate is thedesired end-product.

Crushing and homogenization techniques have been used to manufacturevegetable protein products. These techniques are most frequently used inprotein isolate production. In the isolate manufcture, the protein istypically extracted with either alkali or acid and then precipitatedfrom solution by isoelectric pH adjustment. The extraction process maycause limited protein hydrolysis and protein fractionation occurs as aresult of the isoelectric precipitation thereof.

In U.S. Pat. No. 3,402,165 a high purity vegetable protein product isprepared by finely mashing soybean meal at a pH 3-7 (preferably at itsisolectric point) and screening the mash to separate a non-fibrousfraction from a fiber. The fibrous portion, which contains a smallamount of occluded protein, is passed through a device at a relativelylow temperature to break down the fiberous material by means ofsupersonic oscillations without destroying the fiber structure per se.After washing with water, the purified fibers are recovered and theproteins removed from the purified fiber is combined with the mainprotein fraction obtained as a result of the screening step.

High-viscosity vegetable protein concentrates are reportedly prepared inU.S. Pat. No. 3,723,407 by Miller et al. by subjecting a defatted soyflour slurry at the protein isoelectric point (@ pH 3.5-5.5, 4°-38° C.and 10% d.s.) to centrifugation and differential pressures while passingthe slurry through a shearing orifice under momentary pressure build-upand sudden pressure release (reportedly disrupts the natural cellstructure of the protein), separating the solubles from insolubles(fiber and protein), resuspending the insolubles (@ pH 6.5-8.0 and40°-80° C.) and spray-drying the resultant protein concentrate.

A patent by Egger et al. (U.S. Pat. No. 3,849,391) discloses acontinuous process for producing a vegetable protein product (reportedlylow in trypsin inhibitors and undenatured protein) by jet-cooking adefatted soy flour slurry at a pH other than its isoelectric point. InU.S. Pat. No. 4,018,755 vegetable seed protein are extracted fromdefatted soy flour by sonicating a low solids, alkali flour slurry;centrifuging the sonicate and recovering a water-soluble proteintherefrom. U.S. Pat. No. 3,728,327 reportedly produces protein isolatesby homogenizing a low solids soy flour slurry, centrifuging thehomogenized slurry and recovering the protein isolate from thesupernatant by reverse osmosis.

OBJECTS

It is an object of the present invention to increase the NSI value of avegetable protein product having a low NSI.

Another object of the invention is to increase the level ofwater-soluble protein in a vegetable protein product without causingsubstantial protein hydrolysis or fractionation.

A still further object is to provide an economical and efficient processfor improving the efficacy of the vegetable protein products in aqueoussystems.

It is an object of this invention to provide a vegetable protein whichsimulates the functionality of milk proteins.

DESCRIPTION OF THE INVENTION

According to the present invention there is provided a process forincreasing the water-solubility of a vegetable protein product, saidprocess comprising the steps of:

(A) supplying an aqueous seed feed stream to a homogenizer with saidfeed stream containing on a dry solids basis at least 30% by weightvegetable seed protein and a sufficient amount of base to maintain thefeed stream within said homogenizer at a pH between about 6.5 to 9.0;

(B) increasing the water-solubility of the vegetable seed protein bysubjecting the aqueous feed stream in the homogenizer to successivepressure and cavitation cycling at a temperature between about 50° C. toabout 150° C.; and

(C) recovering the vegetable protein product having an improvedwater-solubility therefrom.

The protein products produced in accordance with this invention haveunique and atypical protein properties. Unlike conventional isolates ofa high NSI which predominantly contain water-soluble proteins with amolecular weight less than 5×10⁵, the water-soluble protein constituentsherein are predominantly comprised of high molecular weight regionprotein aggregates. The reason why the protein product herein exhibitsimproved water-solubility characteristics even though the molecularweight is significantly greater than the prior art water-solublevegetable protein products is not fully understood.

Products prepared in accordance with the present invention exhibit manydesirable properties. Included amongst these desirable improvements areenhanced water-solubility, colloidal, compatibility with lipophiles andhydrophiles, flavor, odor, mouthfeel, binding, fat emulsifying andstabilizing properties. Protein raw materials of a 25 NSI or less (e.g.NSI from about 5 to about 10) are easily converted into a vegetableprotein product having an NSI of 50 or higher. These improvements areachieved without increasing the concentration of water-soluble, lowmolecular weight proteins. Unprocessed raw materials with poor aqueoussolubility and a high proportion of low molecular weight (M.W.) proteinare converted into water-soluble products predominantly comprised ofprotein aggregates having a molecular weight greater than 5×10⁶.Contrary to expectations, such high molecular weight protein aggregatesare water-soluble and improve upon the overall protein solubility of theprocessed product.

Gel chromatography of buffered salt extracts of spray-dried productssubjected to the processing conditions of this invention indicates arearrangement and restructuring of the vegetable protein constituents.It appears as though the process realigns the hydrophilic groups withinthe protein aggregate into a more stable and water-soluble form.Consequently, the processed vegetable protein products may beconcentrated and dried to provide a dried product which will dissolve inaqueous dispersants. Compatibility with lipophiles (in aqueous systems)is apparently achieved by a concomitant more orderly restructuring ofthe lipophilic group to provide, in conjunction with the hydrophilicrearrangement, a product having an improved HLB. Studies upon bufferedsalt extracts obtained from spray-dried products reveal a predominant(meaning greater than any others) protein distribution of proteinaggregates within the greater than 1.5×10⁶ M.W. region relative to thoseprotein constituents respectively found within either the less than5×10⁴ M.W., 5×10⁴ -3.7×10⁵ M.W., 3.7×10⁵ -1×10⁶ M.W. or the 1×10⁶-1.5×10⁶ M.W. regions. Typically the amount of protein aggregate havinga 1.5×10⁶ M.W. in the buffered salt extract will exceed the next mostprevelant protein region (as defined above) by at least 10% and mosttypically by at least 15% by weight.

The restructuring of both the high molecular weight water-solubleproteins into water-soluble protein and the lower molecular weightprotein fractions into larger molecular weight protein aggregatessignificantly reduces the lower molecular weight concentration with aproportionate increase in the high molecular weight protein aggregateconcentration. Protein concentrates, which cannot be effectively placedinto aqueous solution (e.g. NSI 8-10) and containing as the mostpredominant water-soluble constituent, a protein within either the lessthan 5×10⁴ M.W., 5×10⁴ -3.7×10⁵ M.W. or 3.7×10⁵ -1×10⁶ M.W. region, areconverted by the process into a water-soluble, high NSI processedproduct wherein the predominant constituent is greater than a 1.5×10⁶M.W. These results are atypical of conventional water-soluble proteinswhich typically exhibit a predominance of protein constituents withineither the 3.7×10⁵ -1×10⁶ M.W. region (a maximum peak at about 7×10⁵M.W.) or <5×10⁴ M.W. (peaking at approximately 2.15×10⁴ M.W.). Unlikeconventional soy protein products which typically .[. contains.]..Iadd.contain .Iaddend.about 40% or more of the water-soluble proteinconstituents within these two predominant regions, the products hereintypically contain less than 35% by weight and most typically not morethan 25% by weight of its total water-dispersible protein concentrationwithin the 3.7×10⁵ -1×10⁶ M.W. and <5×10⁴ M.W. regions.

On a proportionate weight basis, alteration in protein distributionwithin the five aforementioned regions occurs. Buffered salt extracts ofspray-dried and processed products herein typically contain proteinaggregates of a M.W. greater than 1.5×10⁶ in an amount at least threetimes greater than those within the 1×10⁶ -1.5×10⁶ region and at leasttwo times greater than the proteins found within either the 3.7×10⁵-1×10⁶ or <5×10⁴ region. In contrast, the prior art products typicallycontain a significantly greater proportion of protein within these twolatter regions. Advantageously the products prepared in accordance withthe present invention contain at least four times (preferably at leastabout 5 times) more of the >1.5×10⁶ M.W. proteins than those within the1×10⁶ -1.5×10⁶ region and at least three times (preferably at least 4times) more of these high molecular weight proteins than those proteinsfound within either the 3.7×10⁵ -1×10⁶ M.W. or <5×10⁴ regions. Attemptsto characterize the high molecular weight species present in theprocessed product indicate essentially all the proteins excluded by>1.5×10⁶ gel chromatography are also excluded from a 5×10⁶ M.W. gel.

Illustrative vegetable proteinaceous materials which may be used toprepare the high NSI products herein include low NSI and low fat seedproteins such as defatted proteinaceous materials obtained from grainsand oil-bearing seed materials such as peanuts, cottonseed, soybeans,sesame, rape seed, safflower seed, sunflower seed, corn, wheat, mixturesthereof and the like. Proteinaceous materials from the leguminousoil-bearing seeds are advantageously employed as a protein source withsoy protein being most preferred. Representative soy proteins includedefatted soybean meals or flours, soy protein concentrates (e.g. seeU.S. Pat. No. 3,734,901 by L. P. Hayes et al.), and soy proteinisolates, mixtures thereof and the like. The invention is particularlyapplicable to low NSI soy protein concentrates. Soy protein concentrateshaving NSI values which favorably compare with those historicallyachieved only by chemical or enzymatic hydrolysis and isolationprocesses, such as soybean isolates, may be prepared. Soybean proteinsmanufactured under heat or alcoholic denaturing conditions (e.g.toasting, extraction of lipids and/or water-soluble constituents withalcohol containing solvents or aqueous alcohol) may be likewiseconverted into high NSI products.

The dry solids level of the aqueous feed stream is diluted with asufficient amount of water to permit its conversion from a low to highNSI and PIS product. In general, the water to protein weight ratio inthe starting material will range from more than 6:1 to about 30:1 andadvantageously from 7:1 to about 18:1 with about a 9:1 to about 15:1weight ratio being preferred. An excessively high solids level becomestoo viscous which can create transfer, uniform homogenization processingpH control and product recovery problems. A low solids level isundesirable because of economics and difficulties in achieving theappropriate degree of shear and restructuring of the protein product.

The processing pH materially affects the efficacy of the resultantproduct. During the centrifugal homogenization step, the pH ismaintained within the pH 6.5 to 9.0 range. If the pH is permitted toincrease above the pH 8.5 level with prolonged exposure at processingtemperatures in excess of 150° C. alkaline protein hydrolysis andundesirable lysinoalanine formation can occur. Under normal processingconditions and upon completion of the centrifugal homogenization, thefeed stream alkalinity will decrease by approximately 0.3-0.5 pH units.Thus, the feed slurry alkali adjustment should take into account the pHdecrease which occurs during the processing of the product. Practicalexperience indicates the slurry pH is most suitably adjusted by adding,upon the basis of the protein weight, a predetermined amount of alkalito the slurry which will yield an appropriate alkalinity in theprocessed product. Conventional pH meters and reading devices aregenerally unreliable because of pH drifting.

When reconstituted with water, commercial protein products typically areslightly acidic (e.g. pH 6.0-6.8). Effective conversion into a high PISand NSI product requires an alkaline pH adjustment. Advantageously, thepH adjustment should be sufficient to provide a discharge product pHranging from about 7.0 to about 8.5. The discharge from the centrifugalhomogenizer will typically have about 0.3-0.5 pH unit decrease from thatwhich would normally be expected (i.e. upon amount of base in theunprocessed aqueous feed slurry). This unaccountable change in pH isapparently due to restructuring and exposure of previously occludedcarboxyl groups within the processed product. Further improvements inwater-solubility of the protein product are achievable by adding asufficient amount of base to the aqueous feed stream to provide ahomogenized product having a pH of 7.3 or higher. Advantageously theamount of alkali added to the slurry is sufficient to provide a productdischarging from the centrifugal homogenizer of a pH ranging from about7.5 to about 8.0 with optimum product performance being achieved at aproduct discharge pH of about 7.6 to 7.8.

Although a variety of organic and inorganic bases may be used to adjustthe slurry pH, high NSI products of a food grade are advantageouslyprepared by adjusting the alkalinity of the aqueous feed stream with ametal hydroxide such as the alkaline earth metal hydroxide (e.g. CaOH,etc.) and/or alkali metal hydroxides (e.g. potassium, sodium, etc.hydroxides). The divalent cations of alkaline earth hydroxides are moresusceptible to complex with other complexing indigenous constituents ofthe protein seed material (e.g. proteins, phytins, carbohydrates, etc.).The alkali metal hydroxides are preferred.

When sodium hydroxide is utilized to adjust the aqueous slurry to analkaline pH, a discharge pH 7.0 and pH 8.5 will normally be obtained byemploying from about 0.26 to about 1.1 parts by weight sodium hydroxide(d.s.b.) for each 100 parts by weight protein (d.s.b.). To operate at adischarge pH within the pH 7.5-7.8 range, the amount of sodium hydroxideadded to the slurry (100 pbw protein, d.s.b.) will typically range fromabout 0.8 to about 1.0 parts by weight. A corresponding equivalency ofpotassium hydroxide (about 1.4 times more) is used when it is theadjusting base.

Restructuring of the protein constituents and its conversion into a highNSI product is achieved by subjecting the slightly alkaline aqueous feedstream to successive shear, pressure and cavitation cycling in acentrifugal homogenizer at a temperature between about 50° C.-150° C.The successive and cavitation cycling in the centrifugal homogenizer istypically achieved by a rotor (e.g. a conical impeller, rotating rings,etc.) which accelerates the aqueous stream past a stator or stationaryrings. The rotor and stationary rings are typically comprised of aseries of projections or depressions such as teeth, holes, pins and thelike, operatively arranged at a relatively close tolerance (e.g. 0.25 to1.3 mm). The successive pressure and cavitation cycling causesrupturing, molecular rearrangement and aggregation of the aqueoussuspended dry solids constituents therein. Steam is normally injectedinto the feed port to heat the aqueous feed to the proper processingtemperature and to assist in the cavitation cycling by steamcondensation. In a typical centrifugal homogenizer, the product iscentrally admitted to the centrifugal homogenization chamber,accelerated radially by the conical rotor under high shear anddeflection with cyclic cavitation and pressure occurring as the feedstream is radially accelerated between the projected and recessedmembers of the rotor and stationary rings. Illustrative centrifugalhomogenizers include those which are equipped with a single feed streaminlet as well as those equipped with at least two supply pipes arrangedconcentrically such as disclosed in U.S. Pat. No. 3,744,763 by H.Schnoning et al.

Temperature and discharge pH are significant processing variables whichcontribute towards the PIS of the processed product. The processingtemperature and pH (65° C.-115° C. and pH 6.8-8.5) interrelationship toproduct PIS may be expressed by the following equation:

    PIS=5.7459C-0.1717C.sup.2 -0.22932C pH+606.5 pH-37.8169 pH.sup.2 -2574.6

wherein "PIS" represents the calculated protein in solution (in percent)for the processed product. "C" represents the centrifugal homogenizationprocessing temperature (°C.) and "pH" represents the pH of the productas discharged from the centrifugal homogenizer. The optimum pH effectupon the PIS is between a pH 7.6-7.7 with the more acidic or alkalineconditions at any given temperature resulting in a lower PIS product. Ingeneral, the product PIS at any given pH will increase as the operativetemperature increases. Operation at the optimum pH level (e.g. about pH7.7) permits a lower processing temperature to achieve a high productPIS value with higher temperatures being required to achieve anequivalent PIS level when the process is conducted at a non-optimum pH.The production of a high PIS or high NSI product without thermally orhydrolytically degrading the protein product significantly enhances theoverall functionality of the processed product.

The processing conditions necessary to achieve a particular PIS productfrom the above equation may be empirically calculated. For example, thefollowing coordinate process variables (i.e. pH and °C.) may be used toachieve the following PIS values: pH 6.8 at 109° C. or pH 7.31 at 80° C.or pH 7.8 at 74° C. for a 54 PIS product; pH 6.97 at 115° C. or pH 7.66at 84° C. or pH 7.8 at 83° C. for a 66 PIS product; a pH 7.0 at 115° C.or pH 7.66 at 90° C. or pH 7.8 at 90° C. for a 72 PIS product; and pH7.6 at 115° C. or pH 7.66 at 115° C. or a pH 7.7 at 115° C. for a 84 PISproduct. As illustrated by the aforementioned equation and calculatedcoordinate values, operation at the optimum pH (about 7.7) at any giventemperature will produce a higher PIS product than those processesoperated outside the optimum pH range. Correspondingly a higher "C"contributes towards a higher PIS product.

Pragmatically the minimum temperature for effective production of a PISproduct having a minimum PIS of 55% will be in excess of 75° C., greaterthan 82° C. for a minimum 65% PIS, greater than 88° C. for a minimum 70%PIS, greater than 92° C. for a minimum 75% PIS and greater than 93° C.for a minimum 80% PIS product. Although protein concentrates having aPIS up to about 85 may be prepared, it is difficult to consistentlymanufacture protein concentrates having a PIS in excess of 82.Temperatures in excess of 135° C. are prone to cause LAL and off-flavorproducts and therefore are desirably avoided.

If the starting vegetable seed material contains more than 10%non-protein constituents (e.g. soy flours, concentrates, etc.), theprocessing temperature is advantageously maintained at a levelsufficient to permit the volatilization of undesirable residues (e.g.malodorous, bitter or beany flavors, flatulant, etc. principles)therefrom. This may be accomplished by maintaining the processingtemperature at a level sufficient to permit such undesirable residues tovolatilize therefrom (e.g. 85° C. to about 120° C. undersuperatmospheric conditions coupled with flash cooling to steam distillor flash-off the volatile residues therefrom). The preferred processingtemperature is between about 90° C. to about 110° C.

Other processing variables affecting the NSI and PIS, but to a lesserextent, include rotor RPM, flow rate, head type, rotator and statorclearance, solids level. The head type and clearance will affect thetextural character of the processed product. Coarse grinding heads tendto produce gritty products which may be suitably used for applicationsin which a non-gritty texture is not an essential prerequisite. Forproducts necessitating a non-gritty texture (e.g. dairy, bakeryproducts, etc.) fine grinding heads may be used. Satisfactory productshave been prepared at rotor speeds of about 3500 to 6000 RPM, clearanceof about 0.9 mm to 1.15 mm and flow rates of 2 gallon/min. to 5gallon/min.

The molecular weight of indigenous carbohydrate constituents affects theviscosity characteristics of the processed product.Buffered-salt-extractable carbohydrate constituents of a molecularweight greater than 1.5×10⁶ create more viscous products than thosehaving less than a 5×10⁵ molecular weight. The process does notappreciably increase the amount of low molecular weight carbohydrate inprocessed protein concentrates. The process, however, significantlyincreases the level of water-soluble carbohydrates extractable with the1.5×10⁶ M.W. plus protein fraction. If a low viscosity product isdesired, proteinaceous feed materials which containbuffered-salt-extractable, indigenous carbohydrate constituents of amolecular weight less than 5×10⁴ as a major carbohydrate and less than20% by weight carbohydrate of a M.W. greater than 1.5×10⁶ are utilizedas a raw material source. Low viscosity products are advantageouslyobtained with feed materials which contain at least 75% carbohydrates ofa M.W. less than 5×10⁴ with less than about 10% by weight of thesalt-extractable carbohydrates having a M.W. greater than 1.5×10⁶.Protein concentrates prepared by the hexane-alcohol, (fat) and aqueousalcohol extraction processes (e.g. see U.S. Pat. No. 3,734,901 by Hayeset al.) are a particularly suitable starting material for this purpose.

The processed product may be used in its liquid form or dried to providea product of a high NSI or PIS. The processed product pH isappropriately adjusted to suit its intended end-use. Except for certainlimited applications, most food applications are acidic. Vegetableprotein products at an alkaline pH characteristically possess a soapytaste. In general, the processed protein will be adjusted with an acidto a pH from about 5.0 to about 7.0. In the preferred embodiments ofthis invention, the processed vegetable seed protein product is adjustedto an acidic pH between about 6.0 to about 7.0 with a pH between about6.5 to 6.9 being most preferred.

The present process restructures and stabilizes the protein constituentsinto a form which permits it to be dried into a high NSI vegetable seedprotein product. Although the processed product is less susceptible toheat denaturization than conventional products, drying conditions whichmay lead to heat denaturization of the proteins are desirably avoided.High drying temperatures, semi-dry product (e.g. 100° C.) for prolongedtimes (e.g. 5 minutes) can impair the product NSI. A variety ofconventional drying techniques may be used (e.g. drum-drying, forcedair, freeze-drying, vacuum, fluidized beds, etc.). The processed productis typically dried to a moisture content of less than 10% by weight andpreferably within the range of about 4% to about 8% by weight percentmoisture.

Spray-drying is particularly effective in providing a high NSI product.Spray-drying outlet temperatures in excess of 130° C. tend to yieldlower NSI products than those products prepared at an outlet temperatureof less than 125° C. Advantageously the spray-drying outlet temperatureis maintained between about 70° C. to about 115° C. with an outlettemperature of about 80° C. to about 100° C. being preferred.

The wettability and reconstitutability of the high NSI spray-driedproducts herein in water are similar to those of spray-dried milkpowders (e.g. NFDM). Similar to milk powders, the surfaces of theindividual particles are readily wettable to form a paste which protectsthe interior portion of the particle from further dissolution into theaqueous solution. Upon mixing the pasted surface of the individualparticles will bond together with other particles to form anagglutinated mass thereof. This problem can be corrected by employingconventional techniques heretofore used by the milk industry toinstantize the wettability and reconstitutability of dried non-fat milksolids in aqueous systems.

Analgous to NFDM, spray-driers appropriately equipped with spray-dryingnozzles and operated under conditions to yield particles of a uniformsize, shape and form which will readily reconsitute in aqueous medium(e.g. see Washburn, R. M., 1922 J. Dairy Science 5, 388-389) may be usedto instantize the product. Conventional classification techniques (e.g.air, screening, etc.) will provide appropriately sized particlestherefore. Agglomeration techniques (e.g. see U.S. Pat. No. 2,835,586 byD. Peebles) are also an effective means to provide a product whichreadily reconstitutes into aqueous systems. Another method is by theforminous mat methodology such as disclosed in U.S. Pat. Nos. 3,520,066;3,615,723 and 3,741,273 by R. E. Meade. Aeration techniques which createthin-walled or aerated products such as by spray-drying (e.g. see U.S.Pat. No. 3,505,079 by Meade et al.) or vacuum dried foams may also beutilized to instantize the product. Rapid cooling of the particles (e.g.see U.S. Pat. No. 3,008,830 by Winder et al.) have been suggested as ameans to improve upon the cold-water-dispersibility of the product.

Surface active agents (e.g. see McCutcheon's, Detergents andEmulsifiers, North American Edition, 1977 and column 9, lines 6--column10, line 15 of U.S. Pat. No. 3,620,763 by R. Hans) may be added to thesurface of the dried particles (e.g. see U.S. Pat. No. 2,953,458 bySjollema, French Pat. No. 1,218,803) or agglomerated therewith orincorporated into the processed product prior to its drying (e.g. seetechnique and emulsifiers disclosed by Meade in U.S. Pat. No. 3,505,079)to improve upon its cold-water-dispersibility. Lecithin, ediblenon-ionic surface active agents (e.g. see columns 9-10, U.S. Pat. No.3,620,763 by Hans) such as the fatty acid esters of mono- anddiglyceride (e.g. polyoxyethylene mono- and diglyceride of C₁₂ -C₂₂fatty acids, etc.), the partial fatty acid esters of hexitol anhydrides(e.g. sorbitan fatty esters), the polyoxyalkylene derivatives of partialesters of fatty acids and hexitol anhydrides, mixtures thereof and thelike are particularly useful for this purpose.

An important attribute of products processed in accordance with thepresent invention is the ability to provide a low-viscosity,reconstituted product at high solid levels. This attribute inconjunction with the ability to form high-molecular-weight proteinaggregates or colloids in aqueous systems typifies the uniquefunctionality of lacteal proteins (e.g. non-fat milk solids, caseins,etc.). Accordingly, the high NSI vegetable seed protein products of thisinvention may be utilized as a supplement (e.g. extender) or replacementfor conventional lacteal proteins in a wide variety of food,pharmaceutical and industrial applications. Illustrative culinary usesinclude bakery applications (e.g. breads, pastries, rolls, cakes,doughnuts, cookies, crackers, fabricated or expanded snacks, etc.),cereal and convenience foods (e.g. breakfast cereals, instantbreakfasts, canned foods, etc.), infant foods, confectionaries (e.g.candy, puddings, malted milks, milkshakes, custards, ice cream,toppings, icings, frostings, etc.), processed meats (e.g. poultry rolls,braunschweiger, sausages, frankfurters, weiners, semi-moist pet foods,fish cakes, meatballs, patties, meat loaves, bologna, etc.), filledmilks and other applications wherein caseinates are conventionally used.

The high NSI products herein are particularly useful in formulated foodproducts which contain at least 5% triglyceride (e.g. edible fats andoils). The high NSI products are more compatible with aqueouslydispersed triglycerides and therefore permit higher fat levels to beincorporated into the food product. The water-solubility, exceptionalemulsifying and stabilizing effect coupled with its binding propertiesenhances it functionality in comminuted meat formulations. A stable fatemulsion¹ containing 2% more by weight salt, about 5% to about 30% highNSI vegetable seed protein, about 30% to about 70% water and up to about60% triglyceride may be prepared from the present high NSI and PISprotein. Particular stable triglyceride systems are achieved in aqueousformulations containing from about 45 to about 55 parts by weight waterand about 25 to about 40 parts by weight triglyceride for each 15 partsby weight high NSI protein product. The ability to form stable fatemulsions renders these products particularly suitable for dry mixformulations which contain 5% (by weight) or more triglyceride (e.g.cake mixes, toppings, etc.).

The following examples are illustrative of the invention:

EXAMPLE 1

A low NSI protein concentrate was processed into a 70 NSI product. Thecentrifugal homogenizer employed in this example was a Supraton Model200 Series, manufactured and distributed by Supraton F.J. Zucker KG,Dusseldorf, Federal Republic of Germany, equipped as a Model 247.05 witha fine grinding head, and inlet pipe fitted with a steam injection unitfor temperature control and a discharge pipe (4 ft.) having a terminalcontrol ball valve for back-pressure regulation with internallypositioned pressure and temperature gauges. The inlet pipe to thecentrifugal homogenizer was connected to a mixing vessel for slurrymake-up and pH adjustment. The discharge pipe was connected to aneutralizing mixing vessel for pH adjustment and then spray-dried.

In this example, an aqueous feed slurry was prepared by uniformlyadmixing together in the mixing vessel 1000 parts by weight PROCON²,7000 parts by weight water and 6 parts by weight sodium hydroxide(d.s.b.). The aqueous feed slurry was pumped to the centrifugalhomogenizer at a flow rate of 5 gallons/min. with the steam injectionunit being adjusted to 20-40 psig steam pressure. The centrifugalhomogenizer was operated at 6,150 RPM and 0.9 mm clearance. Theback-pressure in the discharge pipe was maintained at about 30 psig and.Iadd.the temperature to 104° C. The discharge product (pH 7.8) wasneutralized to a pH 6.4 at 71° C. with 10 N HCl. The neutralized productwas then conducted through a high pressure piston pump operated at 2500psig to a concurrent-flow spray drier having a capacity (water) ofapproximately 1,000 pounds per hour, equipped with a No. 51 nozzle and aNo. 425 flat top core by Spraying Systems, Inc., Wheaton, IL. In thedryer, the inlet air temperature was maintained from 210° C. to 225° C.and the outlet temperature from 92° C. to 98° C. .Iaddend.

The NSI of the spray-dried product was determined by AOCS BA1165 -Official Method. The PIS of the product discharged from the centrifugalhomogenizer was determined by taking a 200 gram sample, centrifuging thesample at 5000×g relative centrifugal force for 20 minutes, filteringthe supernatant through Eaton-Dikeman Grade 513, 18.5 cm fluted filterpaper and analyzing the filtrate for percent d.s. and percent protein(Kjeldahl method). The percent protein in solution was then determinedby the following equation: ##EQU1## Gel filtration was conducted uponthe spray-dried high NSI product. Gel filtration chromatography wasperformed on a 1.3 cm I.D.×87 cm column containing Bio Gel A-1.5 m, 100200 mesh resin (Bio Rad Laboratories, Richmond, Ca., Lot 176982). Theelution buffer contained 0.4 M NaCl, 0.1 M TRIS-Cl(Tris[Hydroxymethyl]Aminomethane) and 0.02% NaN₃, pH 7.60. A flow rateof 10 ml/hr. was maintained with a parastaltic pump (Pharmacea FineChemicals, Uppsala, Sweden, Model P-3, 2 mm I.D. tubing). The elutionwas monitored at 254 nM (LKB Instruments, Inc., Rockville, Maryland,Type 4701A) and 1 ml. fractions were collected (LKB Model 7000Ultrorac®).

Individual fractions were assayed for their absorbance at 280 nM(Beckman Instruments, Inc., Fullerton, Ca., ACTA II® spectrophotometer).Proteins were determined as described by M. M. Bradford (1976) in Anal.Biochem., 72, 248-254, "A Rapid and Sensitive Method for theQuantitation of Microgram Quantities of Protein Utilizing the Principleof Protein-Dye Binding" using bovine gamma globulin (Bio RadLaboratores, Lot 17447) as a standard. Total neutral carbohydrates, weredetermined by the method of M. DuBois et al., (1956) Anal. Chem. 28,350-356, "Colorimetric Method for Determination of Sugars and RelatedSubstances" using glucose (Sigma Chem. Co., St. Louis, Mo.) as astandard.

The column was calibrated with proteins of known molecular weightthereby allowing the molecular weight of sample proteins to be evaluated(see P. Andrews (1965) Biochem., J., 96, 595-606 "The Gel-FiltrationBehavior of Proteins Related to Their Molecular Weight over a WideRange"). Standard proteins included Apoferritin (Calbiochem, San Diego,Ca., horse spleen, Lot 601535), Aldolase (Pharmacea Fine Chem., LotDN-11), Conalbumin (Sigma Chem. Co., chicken egg white, Lot 46C-81215),Ovalbumin (Sigma Chem. Co., Lot 18C-8035-1), Chymotrypsinogen(Calbiochem., bovine pancrease, Lot 701586) and Cytochrome C (SigmaChem. Co., horse heart, Lot 48C-7370). The void volume was determinedwith Dextran 2000 (Pharmacea Fine Chem.).

Gel filtration was also performed using a 1.3 cm I.D.×78 cm column ofBio Gel A-5 m, 100/200 mesh resin at a flow rate of 10 ml/hr. The bufferand support equipment was identical to that described for Bio Gel A-1.5m chromatography.

The spray-dried, high NSI samples were treated in the following mannerprior to gel filtration chromatography. A 10 g. sample was extracted forone hour at room temperature with 90 g. of buffer containing 0.4 M NaCl,0.1 M TRISD-Cl (Tris[Hydroxymethyl]Aminomethane), 0.02% NaN₃, pH 7.60.The mixture was stirred (manual spatula stirring for one minute in 150ml. beaker followed by magnetic stirring at medium speed with FischerCatalogue No. 14-511-1V2 stirrer) for 9 minutes after which time, the pHwas adjusted, if necessary to pH 7.60 with saturated NaOH (@ 23° C.).Magnetic stirring was then continued for an additional 50 minutes. Themixture was centrifuged at 12,000×g for 30 min. at 10° C. and an aliquotof the supernatant was subjected to gel filtration chromatography.

For comparative purposes, molecular weight zones were chosen by use ofthe protein molecular weight standard curve. These zones are as follows:>1.5×10⁶, 1.5×10⁶ -1×10⁶, 1×10⁶ -3.7×10⁵, 3.7×10⁵ -5×10⁴, and <5×10⁴.The protein distribution of the sample extract is presented as thepercent of the total protein which elutes within a specific molecularweight region.

The resultant spray-dried soy protein concentrate product (100%particles through a 100 mesh screen) had a 70.1 NSI, a pH 6.7 uponreconstitution with water (@5% solids) and contained 67.3% protein(d.s.b.), 4% fiber, 0.372% sodium, 6.5% moisture and 6.0-6.6% ash. Theprotein and carbohydrate M.W. distribution is similar to those reportedin Run 1 of Example II. Brookfield viscosities (20 rpm at 23° C.) at 5%,10% and 15% (by weight) concentrate levels in water were respectively 20cps, 700 cps and 7750 cps. In order to ascertain the ability of thespray-dried product to form stable fat emulsions, a series of fatemulsions were prepared. These fat emulsions were prepared by weighingout the protein, salt, oil and water; manually mixing in a 250 ml.beaker until smooth; heating in boiling bath with continuous manualmixing to 175° F.; cooling the emulsion to 125° F., and centrifuging 25gm. aliquots in 50 ml. centrifuge tubes for 10 minutes at 281×g relativecentrifugal force (1600 rpm-51/4"). No fat separation was observed forthose test samples having a "Y" value of less than 8.5 per the footnote1 equation given above. The spray-dried product was employed as asubstitute binder for milk protein in a variety of comminuted meatproducts (e.g., frankfuters, liver sausage, weiners, luncheon meats)containing from about 1 to about 15% spray-dried product. Thecharacteristics of the resultant comminuted meat products wereequivalent in quality and workability to the milk protein controlformulations. Conventional layer cakes-dry mixes were prepared byreplacing NFDM and a portion of the egg albumin in the formulation withthe spray-dried product. The quality of the soy protein recipes werecomparable to the control recipes.

EXAMPLE II

Comparative studies were conducted upon a high NSI (Run 1) and low NSi(Run 6) products prepared from a 12.7 NSI protein concentrate (Run 2) ofa slightly lower protein content than the protein concentrate used inExample 1. The Run 2 protein concentrate was obtained by extracting thelipids with hexane/ethanol and the water-solubles with aqueous ethanol.The comparative studies also included the following commerciallyavailable products: Run 3 (concentrate manufactured and distributed byLucas & Co., Ltd., Bristol, England); Runs 4 and 7 (isolatesmanufactured and distributed by Ralston Purina Company, St. Louis, Mo.);Runs 5 and 10 (soy protein concentrates manufactured and distributed byGriffith Laboratories, U.S.A., Alsip, Il.); Run 8 (soy proteinconcentrate manufactured by Garvey Feeds, Muskogee, Okla.); and Run 9soybean I-Grits (flour manufactured by A. E. Staley ManufacturingCompany, Decatur, Illinois).

The Run 1 and Run 6 products were generally prepared in accordance withExample I excepting the following processing modifications: Run 1--Waterto concentrate (d.s.b.) weight ratio 10:1, 0.5% sodium hydroxide(concentrate d.s.b.), 93° C. processing temperature, discharge pH 7.25and 0.037" stator and rotor clearance; Run 6--Water to concentrate(d.s.b.) weight ratio of 7:1, 0.25% sodium hydroxide (concentrated.s.b.), 0.037" clearance, 3500 rpm, 93° C. processing temperature and apH 6.85 discharge.

The comparative products were assayed in accordance with the Example Imethodology, the results of which are reported in the following table.

                                      TABLE                                       __________________________________________________________________________                  Run 1                                                                             Run 2                                                                             Run 3                                                                             Run 4                                                                             Run 5                                                                             Run 6                                                                             Run 7                                                                             Run 8                                                                             Run 9                                                                             Run 10                      __________________________________________________________________________    % Nitrogen (as is)                                                                          10.04                                                                             10.36                                                                             9.83                                                                              14.28                                                                             10.48                                                                             10.48                                                                             12.26                                                                             10.22                                                                             7.78                                                                              --                          % Nitrogen (dsb)                                                                            10.79                                                                             11.01                                                                             10.72                                                                             15.06                                                                             11.38                                                                             11.11                                                                             13.42                                                                             10.88                                                                             8.53                                                                              --                          % Protein (as is) N × 6.25                                                            62.75                                                                             64.75                                                                             --  89.22                                                                             65.48                                                                             65.5                                                                              83.85                                                                             63.85                                                                             48.63                                                                             --                          % Protein (dsb) N × 6.25                                                              67.42                                                                             68.81                                                                             68.7                                                                              94.11                                                                             71.1                                                                              69.42                                                                             93.96                                                                             68.00                                                                             53.30                                                                             --                          % Ash (as is) 6.31                                                                              6.18                                                                              5.04                                                                              3.68                                                                              3.68                                                                              6.22                                                                              3.34                                                                              4.51                                                                              6.10                                                                              --                          % Ash (dsb)   6.78                                                                              6.57                                                                              5.5 3.88                                                                              4.00                                                                              6.59                                                                              3.75                                                                              4.8 6.69                                                                              --                            NSI         72.3                                                                              12.7                                                                              73.2                                                                              1.1 --  39.6                                                                              --  --  --  --                            dry solids  93.07                                                                             94.10                                                                             91.7                                                                              94.8                                                                              92.1                                                                              94.35                                                                             91.36                                                                             93.9                                                                              91.23                                                                             --                            M.W.                                                                        % >1.5 × 10.sup.6                                                                     46.53                                                                             14.98                                                                             36.09                                                                             23.36                                                                             13.59                                                                             58.84                                                                             2.62                                                                              14.94                                                                             14.81                                                                             14.97                       %   >1 × 10.sup.6 -<1.5 × 10.sup.6                                              6.92                                                                              8.85                                                                              15.38                                                                             16.30                                                                             3.89                                                                              12.06                                                                             3.55                                                                              7.17                                                                              14.87                                                                              7.89                       % >3.7 × 10.sup.5 -<1 × 10.sup.6                                                11.52                                                                             23.98                                                                             28.10                                                                             37.70                                                                             26.39                                                                             2.60                                                                              16.16                                                                             25.33                                                                             37.67                                                                             12.88                       %   >5 × 10.sup.4 -<3.7 × 10.sup.5                                              24.62                                                                             25.20                                                                             8.91                                                                              9.64                                                                              30.91                                                                             16.19                                                                             47.07                                                                             34.79                                                                             16.31                                                                             36.13                       %   <5 × 10.sup.4                                                                     11.01                                                                             26.98                                                                             11.52                                                                             13.60                                                                             25.21                                                                             10.30                                                                             30.59                                                                             17.78                                                                             16.34                                                                             28.13                       __________________________________________________________________________

The chromatogrpahic protein fractions for Run 1 and Run 6 were alsoanalyzed for water-soluble carbohydrates. For the unprocessed proteinconcentrate (Run 2), 95.13% by weight of the carbohydrate wasfractionated with those proteins having a M.W. of less than 5×10⁴ withthe balance (4.87%) being excluded with the protein fraction having aM.W. greater than 1.5×10⁶. In contrast, the processed product of Run 1contained 69.15% by weight carbohydrate of a M.W. less than 5×10⁴ withthe carbohydrate balance (31.49%) being found along with the proteinfraction of a greater than 1.5×10⁶ M.W. The actual amount ofcarbohydrate having a M.W. less than 5×10⁴ between Runs 1 and 6 remainedrelatively constant while the level of water-soluble carbohydrate havingan apparent M.W. greater than 1.5×10⁶ was increased in Run 1. Thewater-soluble, high molecular weight carbohydrates may compriseglyco-proteins (i.e., carbohydrates covalently linked to protein) orwater soluble carbohydrates or mixtures thereof. The carbohydrateshaving a M.W. less than 5×10⁴ consists essentially of carbohydrates ofless than 1×10⁴ M.W. and are believed to be primarily comprised ofcarbohydrates having a D.P. of less than 5. Comparative studies indicatea major proportion of the greater than 1×10⁶ M.W. carbohydrate extractsand a significantly smaller weight percent of the lower molecular weightcarbohydrates for the Run 10 product.

We claim:
 1. A process for improving the water-solubility of a vegetableprotein product said process comprising the steps of:(A) supplying anaqueous vegetable seed feedstream to a homogenizer with said feed streamcontaining on a dry solids basis at least 30% by weight vegetable seedprotein and a sufficient amount of base to maintain the feed streamwithin said homogenizer at a pH between about 6.5 to 9.0, (B) increasing.Iadd.(i) .Iaddend.the water-solubility.Iadd., as ascertained by NSI,and (ii) the aggregate molecular weight .Iaddend.of the vegetable seedprotein by subjecting the aqueous feed stream in the homogenizer tosuccessive pressure and cavitation cycling at a temperature betweenabout 50° C. to about 150° C.; and (C) recovering the vegetable proteinproduct having an improved water-solubility therefrom, .Iadd.said feedstream being homogenized in a centrifugal homogenizer, the aqueousvegetable feed stream comprising a soy protein concentrate characterizedas having an NSI of less than 25, containing (on a buffered ashextractables weight basis) carbohydrate constituents of less than 5×10⁴molecular weight as the major carbohydrate and less than 20% by weightcarbohydrates of a molecular weight greater than 1.5×10⁶, said soyprotein concentrate containing as its most predominant water solubleconstituent, a protein within either the less than 5×10⁴ M.W., 5×10⁴-3.7×10⁵ M.W. or 3.7×10⁵ -1×10⁶ M.W. regions, the pH ranging from about6.8 to about 8.5, the temperature ranging from at least 65° C. to about115° C. with said temperature and pH being sufficient to provide a PISof at least 55% as determined by the following equation:PIS=5.7459C-0.01717C² -0.22932C pH+606.5 pH-37.8169 pH² -2574.6wherein"PIS" represents the percentage of protein in solution for the productof step (B), "C" represents the centrifugal homogenization processingtemperature in centigrade degrees and "pH" represents the pH of theproduct as discharged from the centrifugal homogenizer, said producthaving an NSI of at least 55% and containing (on abuffered-salt-extractable protein weight basis) protein aggregates of amolecular weight greater than 1.5×10⁶ as a predominant proteinconstituent relative to the weight percent of protein constituentsrespectively within either the less than 5×10⁴ molecular weight region,the 3.7×10⁵ -1×10⁶ molecular weight region or the 1×10⁶ -1.5×10⁶molecular weight region; and the weight percent protein aggregateshaving a molecular weight greater than 1.5×10⁶ exceeding the weightpercent proteins in each of the other regions by at least 10 weightpercent and is at least three times greater than the weight percent ofprotein within the 1×10⁶ -1.5×10⁵ molecular weight region. .Iaddend. .[.2. The process according to claim 1 wherein a sufficient amount of baseis added to maintain the pH between about 7.0 to about 8.0..]. .[.3. Theprocess according to claim 2 wherein the vegetable seed proteincomprises soy protein..].
 4. The process according to claim 1 whereinthe weight ratio of water to seed protein (on a dry substance basis)ranges from about 9:1 to about 15:1 .[.and the temperature ranges fromabout 85° C. to about 120° C..].. .[.5. The method according to claim 4wherein the aqueous vegetable seed feed stream is subjected tosuccessive pressure and cavitation cycling in a centrifugalhomogenizer..].
 6. The process according to claim .[.5.]. .Iadd.1.Iaddend.wherein the base comprises an alkali metal hydroxide. .[.7. Theprocess according to claim 6 wherein the vegetable protein product isrecovered by adjusting the product obtained from step (b) to a pH fromabout 5.0 to about 7.0 and then dried to provide a dry product having anNSI of at least 55..]. .[.8. The process according to claim 6 whereinthe vegetable seed protein consists essentially of a soy proteinconcentrate..]. .[.9. The process according to claim 8 wherein the pH isat least 7.3, the water to protein vegetable weight ratio ranges fromabout 7.1 to about 18.1 and the temperature ranges from about 90° C. toabout 120° C..]. .[.10. The process according to claim 1 wherein thefeed stream is homogenized in a centrifugal homogenizer, the aqueousvegetable feed stream comprises a soy protein concentrate characterizedas having an NSI of less than 25, containing (on abuffered-salt-extractables weight basis) carbohydrate constituents ofless than 5×10⁴ molecular weight as the major carbohydrate and less than20% by weight carbohydrates of a molecular weight greater than 1.5×10⁶ ;the pH ranges from about 7.5 to about 8.0, the temperature ranges fromat least 75° C. to about 115° C. with said temperature and said pH beingsufficient to provide a PIS of at least 65% as determined by thefollowing equation:

    PIS-5.7459C-0.01717C.sup.2 -0.22932C pH +606.5 pH-37.8169 pH.sup.2 -2574.6

wherein "PIS" represents the percentage of protein in solution for theproduct of step (B), "C" represents the centrifugal homogenizationprocessing temperature in centigrade degrees and "pH" represents the pHof the product as discharged from the centrifugal homogenizer..]. 11.The process according to claim .[.10.]. .Iadd.1 .Iaddend.wherein thecentrifugally homogenized product is adjusted to a pH ranging from about6.0 to about 7.0 and recovered by drying in a spray dryer at an outlettemperature of less than 115° C. .[.12. A vegetable seed protein productcharacterized as having an NSI of at least 55% and containing (on abuffered-salt-extractable protein weight basis) protein aggregates of amolecular weight greater than 1.5×10⁶ as a predominant proteinconstituent relative to the weight percent of protein constituentsrespectively within either the less than 5×10⁴ molecular weight region,the 5×10⁴ -3.7×10⁵ molecular weight region, the 3.7×10⁵ -1+10⁶ molecularweight region or the 1×10⁶ -1.5×10⁶ molecular weight region; and theweight percent protein aggregates having a molecular weight greater than1.5×10⁶ exceeds the weight percent proteins in each of the other regionsby at least 10 weight percent and is at least three times greater thanthe weight percent of protein within the 1×10⁶ -1.5×10⁵ molecular weightregion..]. .[.13. The vegetable seed protein of claim 12 wherein thevegetable seed protein consists essentially of soy protein..]. .[.14.The soy protein product of claim 12 wherein the weight percent ofprotein aggregates having a molecular weight greater than 1.5×10⁶ is atleast two times greater than the weight percent of proteins withineither the 3.7×10⁵ to 1×10⁶ region or the less than 5×10⁴ region..]..[.15. The product according to claim 12 wherein the product comprises asoy protein concentrate and essentially all of the protein aggregateshaving a molecular weight in excess of 1.5×10⁶ also have a molecularweight greater than 5×10⁶..]. .[.16. The soy protein concentrate productaccording to claim 15 wherein the weight percent of protein aggregateshaving a molecular weight greater than 1.5×10⁶ is at least four timesgreater than the weight percent of proteins within the 1×10⁶ -1.5×10⁶molecular weight region and at least three times greater than the weightpercent of proteins within either the 3.7×10⁵ to 1×10⁶ molecular weightregion or less than 5×10⁴ molecular weight region..]. .[.17. The soyprotein concentrate product according to claim 16 wherein the producthas an NSI of at least 60%, the weight percent of protein aggregateshaving a molecular weight greater than 5×10⁶ is at least 15% greaterthan the weight percent of proteins within either the 1×10⁶ -1.5×10⁶molecular weight region, the 3.7×10⁵ -1×10⁶ molecular weight region, the3×10⁴ -3.7×10⁵ molecular weight region or the less than 5×10⁴ molecularweight region..]. .[.18. The product according to claim 17 wherein thewater-soluble carbohydrates extractable with the protein fraction havinga molecular weight less than 5×10⁴ constitute, on a carbohydrate weightbasis, the major extractable carbohydrate of said soy proteinconcentrate..]. .[.19. The product according to claim 18 wherein atleast 65% by weight of the water-soluble carbohydrate of the soy proteinconcentrate is comprised of carbohydrates having a molecular weight lessthan 5×10⁴ with the balance of the carbohydrate being comprised ofwater-soluble carbohydrate of a molecular weight of greater than1.5×10⁶..]. .[.20. In a food composition containing carbohydrate and awater-soluble protein, the improvement which comprises replacing atleast a portion of the water-soluble protein with a water-solublevegetable seed protein characterized as having an NSI of at least 55%and containing (on a buffered-salt-extractable protein weight basis)protein aggregates of a molecular weight greater than 1.5×10⁶ in anamount exceeding by at least 10 weight percent, the weight percent ofprotein constituents respectively within either the less than 5×10⁴molecular weight region, the 5×10⁴ -3.7×10⁵ molecular weight region, the3.7×10⁵ 1×10⁶ molecular weight region or the 1×10⁶ -1.5×10⁶ molecularweight region; and the weight percent of protein aggregates having amolecular weight greater than 1.5×10⁶ is at least three times greaterthan the weight percent of protein within the 1×10⁶ -1.5×10⁶ molecularweight region..]. .[.21. The composition of claim 20 wherein thevegetable seed protein consists essentially of soy protein..]. .[.22.The composition of claim 20 wherein the weight percent of proteinaggregrates having a molecular weight greater than 1.5×10⁶ is at leasttwo times greater than the weight percent of protein within either the3.7×10⁵ -1×10⁶ molecular weight region or the less than 5×10⁴ molecularweight region..]. .[.23. The composition according to claim 20 whereinthe weight percent of protein aggregates having a molecular weightgreater than 1.5×10⁶ is at least four times greater than the weightpercent of proteins within the 1×10⁶ -1.5×10⁶ molecular weight regionand at least three times greater than the weight percent of proteinswithin either the 3.7×10⁵ -1×10⁶ molecular weight region or less than5×10⁴ molecular weight region..]. .[.24. The composition according toclaim 20 wherein the product has an NSI of at least 60%, the vegetableseed material consists essentially of a soy protein concentrate, theweight percent of the protein aggregate of a molecular weight greaterthan 1.5×10⁶ is at least 15% greater than the weight percent of proteinswithin either the 1×10⁶ -1.5×10⁶ molecular weight region, the 3.7×10⁵-1×10⁶ molecular weight region, the 5×10⁴ -3.7×10⁵ molecular weightregion or the less than 5×10⁴ molecular weight region..]. .[.25. Thecomposition according to claim 24 wherein the composition contains anemulsion comprised of soy protein concentrate, water and triglycerideoil in amounts as defined by the equation:

    Y=-807.86+0.1132 W.sup.2 +0.3285 P.sup.2 +15.579 9 O-0.06458 O.sup.2

wherein Y represents a value of less than 8.5, P, W, and O respectivelyrepresent the water-soluble soy protein concentrate, water and oilweight percents.